Oscillograph galvanometer



Feb. 6, 1945. c.M. HATHAwAY 2,363,831

l QscILLoGRAPH GALvANoMETER Filed sep't. 19, 1942 l 2y sheets-sheet' 1 Feb. 6, 1945. M HATHAWAY 2,368,831

OSGILLOGRAPII GALVANOMETER Filed Sept.- 19. 1942 2 Sheets-Sheet 2 l l l l Patented Feb. ,6, 1945 OSCILLOGBAPH GALVANOIVIETER l. Claude M. Hathaway, Denver, Colo.

Application September 19, 1942, Serial No.' 459,055 l My invention relates to galvanometers andv more particularly to galvanometers vfor oscillographs.

-While numerous types of oscillograph galvanometers have been devised, generally they have been quite complicated and relatively expensive to manufacture. Galvanometers for oscillographs require high precision work and generally the quantities manufactured are relatively sma11 so that it is diicult to gain theadvantages of mass-production. Therefore it would be highly desirable to provide an improved galvanometer which is rugged, accurate and yet inexpensive to manufacture. One of the factors which contribute greatly to the expenses of manufacture is the. time and care necessary to accurately 'position the galvanometer element between the pole-tips of the magnet, particularly in the case of bilar galvanometer elements. Furthermore it would be desirable to provide a means for lkeeping relatively constant the damping effect of the oil in which the biiilar element is suspended, and also to provide readily accessible means for adjusting the tension of the galvanometer element. These and other desirable features may be obtained inaccordance with the present invention whereby a cell box is provided which is relatively simple to construct and which is provided with a piloting device for accurately positioning the galvanometer element with respectto the pole pieces. Means are also provided for permitting the oil to expand with temperature changes so as to maintain more con- Stant the damping action thereof.

It is therefore an object of my invention to provide a new and improved galvanometer structure which will overcomethe abovementioned disadvantages heretofore found in the prior art.

Another object of my invention is to provide an improved type of cell box which will be relatively simple to manufacture. 'Y

Still another object of my invention is to provide a galvanometer cell box'with Ameans whereby the galvanometer element may be quickly and accurately positioned with respect lto the'poletip members.

A still further object of Amy invention is to provide a galvanometer element tensioning means which is readily accessible upon removal of an oil filler plug. l 4

A still further object of my invention its to provide an arrangement whereby the damping eect of the oil in the cell box will remain more'nearly constant over a range of temperatures.

Other and further objects of my invention will (Cl. IVI-95) be more readily appreciated by reference to` the 'following description takenin connection withthe accompanying drawings wherein Figure 1 is an assembled view showing 'a galvanometer incorporating the features of my invention; Figure 2 is av front view of a galvanometer cell box in assembled relationg'Figure 3 is a front view of the galvanometer cell box with the front plate or cover removed therefrom; Figure 4 is a top view of the sides and back of the cell box; Figure 5 is an exploded prospective View of the members forming the sides and back of the galvanometerv cell box; Figure 6 is a, cross-sectional View of the `oil ller chamber wherein thereis positioned an adjustable means for regulating the tension on the bifllar galvanometer element; Figure 7 is a cross-section along the line 'I--l of Figure 6; Figure 8 is a cross-section along the line 8 8 of Figure 6; and Figure 9 is a cross-section of the oil ller plug which' is adapted to be mounted in the oil filler chamber shown in Figure 6.

. Referring to Figure l, there is shown a side View of an improved galvanometer having a base II which supports a base plate I2 upon a pivot I3. Upon the base plate I2, there is positioned lanother plate I4 which is angularly movable with respect to the plate I2 and the base II. Since the plate I 4 is secured in such relation to the plate I2' by means of suitable fastening means l5 which extend up to the bottom of a galvanometer' cell box I6, the horizontally pivoted plate I2 may have the rear end 'thereof elevated by adjusting an operating mechanism I1 which'may be any one of the types well known in the art. The operating mechanism Il Operates against a spring biasing means contained within the cylindrical enclosure I8. The

-upper plate I4 is angularly movable with respect to the plate I2 of the base II by means of the` operating mechanism connected tothe shaft It.y

. This operating mechanism also is of a type well known in the art. These adiusting means I1 and I9 are provided so' that the light reflected from the mirror Supported by the bifllar galvanometer element may be directed at a desired point on a screen vor a. film-in an oscillograph. At the rear of the cell box I6, there is provided a permanent magnet 2| which supplies a. magof the cell box.

By referring to Figure 2 in conjunction 'with Figure 1, it will be seen that the cell box IG is provided with a-front plate 22 secured in posi'- .portion tion by suitable fastening means 23..' At the up# per end of the front plate 22 there is provided a, binding post 24 which is connected to one end an oi1 ller reservoir`25 having a ller cap 26. The oil reservoir 25 'contains adjustable tension .of a bifllar galvanometer element. Near the l bottom of the front platev 22 there is provided means which subsequently will be described and -which is shown in Figure-6.V The front plate 22 v i is 'also provided with a pair of insulated bridge, -,members $1 upon which the bilar element is thereis provided a-lens holder29 secured to the `front plate by suitable fastening means il. The

lens holder has an inwardly extending portion 32 which cooperates with a suitable recess formed inthe cell box side members. l

By referring to Figures 3, 4, and 5, it will be seen that the cell box in additionV to the front plate 22 comprises. a block -of material 33 havingat the rear thereof a transverse recess., 34 and Vbeing provided with anel'ongated longitudinal recess 55, which adjacent the central portion thereof` has a pair of'recesses 36 into which the extended portion 32 of ,thelens holder 29 is arranged Vto iit. Thus the `block of material 33 partially suppliesk the sides and the back of thece box l5. Fitted into the transverse re y eess- 34 Vare a pair of pole pieces, preferably of softiron, each of which Ahas pole tip portions 38` extending toward the longitudinal center of the blockfof material'. Each of the pole tip portions-88 adjacent the center thereof is provided with a recessed portion 39 so as to provide an opening wherein a mirror supported upon the biiilar galvanometeiI element may rotate inV ac cordance-with the electrical energy being sup-- plied to the biilar element. The opening remaining-at the rear Iof the block of material 33 when lthe pole pieces 3T are in position is closed by a back plateyl. preferably secured in position on the block of material 38 by'sweating although it will be seen that these pieces are furthermore provided with suitable apertures so that the mounting screws 2a on :the front plate 22 may extend 'through the Afront plate 22, through the block 33 and into the pole pieces 31; The back plate also may be secured by sweating, soldering or by fastening means-such as cap screws. v

Inthe manufacture and assembly ofthe cell box I6 a block of material such as 53 is iirst` provided with a transverse recess 34 and the' longitudinal recess '35. The arcuate `recesses 5%' are formed -at the proper place adjacent the longitudinal recess 55'. "Thereupon the Vpole' pieces 31 are mounted and secured' lilv sweating..

filler reservoir i5 `tarifliche mechanism contained thereon, and 'the lens holder' 23 is'. secured in' The pole pieces 31 arev and accurately positioned in the proper relationto the pole tips 38 and the notches 35'.

l Reference may vnow be had to Figures 6,-7, and 8 from which the construction and operation of the adjustable 'means forfregulating the tension of the bilar element-will be understood.. As has previously been stated, the upper ends of the bilar element 43 areconnected tothe binding post 24 and the stud' 28 and then are passedover apair or bridge members 21 to a pulley wheel 44 which .'s'mountedat the end of a bell crank 45. The bell crank 45 is pivotally supported by a member 46 which at the central portion has a substantially cylindrical conguration 41 which conforms to the interior of the This cylindrical configuration however is provided with recessed poroil ller reservoir 25.

tions so that certain elements of the adjusting mechanism may move therethrough. Extending from one .end of the central portion 41 there is abifurcated portion 48 between which there 4is supported the bell crank'l45. AAt the' other end of the central portion 41 there is provided an extending portion 49 which has .a depending portion at the end thereof 5I. 'Ibis depending portion 5| is bifurcated so as to Support a screw member 52. The screw member- 52 has a threaded portion in engagement with a. threaded aperture in the plug 53 which is providedvwitli an upA-right pin 54 operating within a narrow guide which is in alignment with the bifurcated portion 48 and with the slotof the bifurcated depending member 5l. The pin 54 therefor prevents the plug 53 from turning whenever the screw 52 is being adjusted. Adjacent one end of I spring 55 the other end of which is in engagelment with the other arm of the. bell crank 45.

Thus adjustment of `the screw 52 will cause the plug 53 to be movedlongitudinally in'Figure 6' so as to increase or decrease the tension asserted by the spring 55 upon the bell crank 45 and thereby regulating the tension of the bifllar element 43. It'will be notedv that the head of the screw 52 is positioned within the threaded opening 56 of the oil ller receptacle 25 so as to be readily accessible whenever theI ller plug 29, shown in detail in Figure 9, has been removed.

The oil ller plug shown in Figure 9 which cooperates with the threaded aperture 56 of the oil reservoir 25 comprises a knurled portion 2S having a. reduced portion 51 provided with threads for cooperation with the threads in the vided vwith anvopening 59 in communication with a recessed portion 8| the face of the oil filler plng25. Be.

' and the 'back plate issecured Yin position. front Plate "22 is lti'xercupon provided with lvof the oil ller 51 is a suitable gasket 58, so that a proper seal 'opening se'. vPositioned adjacent theporuon 2s plug and adjacent the threads may be obtained. The threaded portion 51 is proextending so as to be formed in Y tween the recesses 55 and 51, there is positioned a. .nexihle expansion diaphragm 62 which pref- A oil. This diaphragm 62 is, retained in position by a wedging ring 63. By providing communi-f position. The ngaalmanoineiver element .is-then 1 strung upon this. assembled plate. the iront' plate is placed upon the block 35am! a. gasket 42 is preferably interposed sof'thaty use ofthe fastening means z3 the een box is may be v,mme fluid tight. By'virtue of the fact y cation' fromthe interior-pf the oil reservoir'ierably is formed of an elastic resilient synthetic material which will withstand vthe action o! the to the diaphragm of the oil ller plug 28 the damping action of the oilin the 'cell box will be maintained morenearly constant over' a desired. range of operating temperatures. A'resil ient'expansion diaphragm 62 which is not aftested bythe oil permits the oil pressure to'be relieved spuiciently sok-that the damping action of the oil on thedmirrorsuspended on the bllar element is more nearly constant, thereby greatly increasingthe accuracy of the indication given by the galvanometer.

In accordance with my invention therefore,

there has been provided a galvanometer cell box with the back side of said block, a rear cover which may be manufactured economically and d which yet will retain all the characteristics and features generally desired in such structure.l The cell box is provided with guide means for receiving the lens holder. of the galvanometer cell so that the galvanometer element is accurately positioned within the cell between the tips of the pole` pieces. relatively constant over the normal operating temperatures and the tension of the galvanometer element-may be readilyadjusted by removing the oil ller plug.l These features. cooperate to permit an economical manufacture of a highly accurate galvanometerfor scientific and industrial uses. 1

While a preferred embodiment of my invention has been'shown'fand described, it of course is to be understoodthat modifications may be made therein without.departing from the spirit and scope of my invention as set forth in the appended claims. l

What I claim as new and desire to secure Letters Patent of the United States is:

l. In anroscillograph galvanometer, a cell 'box having an elongated block of material provided across the rear surface thereof` with a transverse recess for receiving a pair of pole tip members, and being provided with a longitudinal aperture perpendicularto the front and back of said-block for receiving a movablel galvanometer element vand mounting means therefor whereby said movable galvanometer element may be positioned be-V tween said pole tip members.

2. In an oscillograph galvanometer, a cell box? having a substantially rectangular block of nonmagnetic material provided across the rear surface thereof with a transverse recess for receiving a pairv of pole tip members, said block being provided between the front thereof and said recess The damping action of the oil is with a longitudinal aperture for receiving a galvanometer element and mounting means therefor whereby said element may beA positioned be-y tween said. pole tip members, said longitudinal aperture being provided with recessed portions for receiving a portionl of a lens holder.

3. In an oscillagraph galvanometer, a cell comprising a block of non-magnetic material provided at the rear thereof with a transverse recessand provided between the front and said recess with an elongated aperture having recessed portions, a pair of poletip members mounted in said rear recess so'as to be flush with the back side of said block, a cover plate for closing the aperture remaining between the faces of the spaced pole tip members, 'a front plate for said box, said front plate being provided with a movable galvanometer element supported therefrom, said eles ment being positioned within said elongated aper-`4 ture, said front plate being provided -with an aperturerhaving a lens holder mounted therein, said lens holder having a portion extending into the recessed portions of the elongated aperture of said block. Y I v 4. In an o scillograph galvanometer, a cell comprising a substantially rectangular block of nonm'agnetic material provided at the rear thereofV with a transverse recess and provided between said recess at the front thereof with an elongated aperture having adjacent the center portion;

` of synthetic elastic material.

bers mounted in said rearrecess so as to be ush plate for closing the rear of the aperture remainf' ing between said pole tip members, a front plate said recess and the front with an elongated aper-V ture providedwith reces'sed'portions, a pair of pole tip members secured in said transverse recesar-,a front plate for sealing said cell, said front Vplate supporting a movable galvanometer element and'being-provided with means engaging said recessed portions of said aperture whereby said movable element is accurately positioned between said elongated pole tips.

6. In an oscillograph galvanometer, a cell comprising a substantially rectangular block of nonmagnetic material provided with a transverse recess across the rear surface thereof and between said recess and the front thereof with an elongated aperture, a pair of pole tips secured in said vrecess by sweating, means for sealing said cell including a front plate provided with mougiting meansarranged to extend into said elongated aperture to position accurately a movable galvanometer element between said pole tips.

7'. In an oscillograph galvanometer cell, an elongated block of material having front and back surfaces of grater area than any other surface and provided across the back surface thereof with a transverse recess and with a longitudinal aperture extending between the front and back, and aA pair of pole tip members mounted longitudinally in said recess, said members having relatively narrow pole tip surfaces spacedl apart in thel proximity of the longitudinal central axis of said block. Y

8. In an osclllograph galvanometer cell, an elongated block of non-magnetic material having front and 'back surfaces of greater areathan any other surface and provided at the rear with a transverse recess and with a longitudinal aperr ture extending -between the front and rear, and' a pair of magnetic pole tip members mounted apart in the proximityoi' the longitudinal cen- A trai axis of said block.

9. In an oscillograph galvanometer comprising i a'vclosed cell box supporting a pair of pole piecesy a iilar galvanometer element positioned between said pole pieces, means for filling said cell bOX F with oil, and means for permitting said oil tol l expand 'comprising an oil expansion diaphragm l0. An oscillograph galvanometer comprising a closed cell box supporting a pair of pole pieces, a filar galvanometer 'positioned between said pole pieces, means fortlling said cell with oil, and means for insuring relatively constant dam-ping action of the oil comprising diaphragm of synthetic elastic material positioned kbetween the interior and the exterior of said cell box.

thereof recessed portions, a pair of pole tip mem-` i 1 Amoscillogmphgalvannmetex: cell ing @rectangular block having a: longitudinaglaplerture 'provided-'with .recessed portions, a pair" of pole: .tips-` supported..1 adjacent said :aperture: a front :plate .for 'saith blockmavingotherein. an :ap-

erture, a; larelementfsupported by; said. front lplate, a -lens holder mountedgon said p1ate;and

e having'v Y a: A:portionvv ...extending therethrough. into receptacle. vso as '.to fbeaccessible .for adjustment .whensaidcover is removed, and means for maintaining. relatively 2constant damping action of-athe .oil-in said cell-,.saiimeans comprising. an elastic rsynthetiozdaphragm snounted insaid receptacle cover.

`:12.1111:moseillograplrgalvanometer, v a. cell'lbox :having a. blockormateria provided fwithan elon- ,gatedraperturefhavingaacent :thefcenter thereoff recessed portions for receiving aportionlof a lens holder, a front {.vlate-forrsaidl box-.provided with a. movable galvanometer element .supported -.tl1er 'eby,zsaid front plate xheing provided adjacent thecenter; thereof: with anaperture, and a; lens :Lai Y I y y ons-aid.block` wheneby. the positiomoi-saidzbiiar .lei'exnentl isa-predetermined withfrespect-toesaid .cpoleytips 14. In an oscillograph -galvanometencellzroomsipsingf az-.zsubstantially- .rectangular-,.-falon'gated :.-bleck of..`;nonmagnetic material.. a front cover ';plate, aiflenszheldenand a. rear cover. platerasaid ,block of;mza.t'e1'lalshavingv adjacent the Acenter a ntransversezrecesszand between the front andhack 10a-thereof, ajongtudinally .elongated aperturesv a of'poleftipsfmounted in'. said recess-so as. to beush'with the .outer surfaces of said block,

said rear cover plate closing' the back" of said. elonf.. gated-aperture, said' front coverplateibeingmron 1:5 wided'witlr mounting means -supporting'thereon a movable galvanometerl elemeim-` said.. front;cover pato;-being;provided with an aperture, saidlens .hoderzbeing-mounted on-said cover plate sofas toextend through the aperture. thereof, said lens -201holderheing3adapted to t into a portion ofnthe elongated aperture i'n said block therebytmproperlyfzmsition the .galvanometerelement.- relative tosaid polertips. Y l l :15.Ing an oscillograph galvanometervcell; com- Y 25o-prisme.v a substantially rectangularl elongated block; of nonmagnetic material, a;front cover plate, a lens holder and a' rear cover-plate, said 'rbloclr o-f material having at the rearv thereof` adjacent the--centerf a transverse recess :and beholder mountednnsaldfront plate'and extendingwsof tween the front and back thereof a longitudinal- :through-said :aperturer: said lens holder-having a` .member commementaryto said, aperture ofzsaid lfrontrplateeand to theirecessed portionsofssaid 'elongatedaperture-thereby .determining .the posihaving. alibleck 'of nonfmagnetic material supporting apain of magneticpole-tip members, said hlockpeingzprovided: at.;the.- front thereof with :an zeiongateckaperturexhaving. :therein recessed'.

ly elongated aperture provided at ltheirontada'acent the -center thereof with arcuate recessed portions, a pair aof pole tipsmounted ini-.said rear recesszso as to .be flush with the backand Ytienta fi-thefgalvanorneter,'element in;said.cellhox5.:35 sides oi said block, said rear cover platelosing 5.13.'.-111amoscillograph galvanometer, aP cell box the back ofsaid elongated aperture, said front cover :plate being provided with mountingmeans supporting therein a movable bilar galvanometer element, said front cover .plate being prof 40.vided adjacent the center thereof with anap'er- 45 aperture thereby to properly positlon'thefgalvanometerV element relative to'said pole tips.

CLAUDE M. HA'IHAWAY. 

